This invention applies to electricity generation for the home and also for industry and institutions. The utility grid that powers homes and industry in the U.S. has huge capacity and spinning reserve. A home connected to the grid can use 1,000 kW-hrs or 5 MW-hrs and the grid is not affected. On the other hand, a home with constantly changing loading, powered by a generator goes through large capacity requirements over the course of the day and from season to season. One way to accommodate the large capacity swings is to use a generator that can operate to deliver 20 Watts, 44-kW, or zero Watts, instantly as loads in the household require. However this would be too expensive to consider. The operating cost of a 44-kW generator operating under constantly changing loading would also be uneconomical. The alternative is to install a much smaller, less expensive generator that is less expensive to operate, powering only loads that are required during a grid-out emergency. This invention provides a way to use a small, very efficiency generator, preferably operated with heat produced by the sun, stored for day and nighttime use. This system makes use of the grid, in a non-feedback manner, to assist in powering the upper load requirements for electrical power in the home. By remaining connected to the grid and generator, the household enjoys seven 9s reliability, the occupants oblivious to grid outages. Connected to the grid, the utility has at it's disposal nearly double the generating capacity from homes during times of grid overload by bringing online home-generated power as needed to satisfy the overloading. The utility can also utilize this feature to switch off and insure that all grid-feeding is off while distribution wiring is being repaired. The advantage to electric utilities will be instant capacity to maintain the grid and fewer, smaller, and more efficient generator plants, thereby reducing pollution.
Thermoelectric devices have been used for many years for specific applications where the simplicity of design warrants their use despite a low energy conversion efficiency. Thermoelectric generators and thermoelectric chillers have been improved in efficiency to a point where it is now practical to use them to power all the electrical and air conditioning needs for the modern home. Independent home electrical and air handling systems that normally require the combustion of carbon-based fuels, can now be operated on stored heat derived from sunlight. Solar heat, concentrated and stored for operation as needed, can be used during daytime or nighttime, year round. A unified connection means for home electric systems is needed to comply with fire safety and energy regulatory agencies, yet provide easy to install, seamless, uninterrupted electrical service for the home. The ability to make use of the grid in times of generator failure and the ability to call on the generator in times of grid brownout and failure provides the home with seven 9s reliability. Seven 9s reliability is required by most electronic systems, as opposed to the normal four 9s electric service reliability provided by grid-only service.
The voltage produced by a thermoelectric device depends on the Seebeck voltage of the dissimilar metals used. Seebeck voltages are higher for some semiconductor materials especially n-type and p-type elements made primarily of mixtures bismuth, tellurium, and antimony.
To compete with more traditional forms of heat to electricity conversion thermoelectric devices must be defect free and to be as efficient as possible. A preferred means to achieve such high efficiency is to arrange the thermoelectric element in a circle with only a very small region used to extract the energy produced by the thermoelectric elements. Patent PCT/US97/07922 to Schroeder discloses such a circular arrangement. Art teaching in this case is focused on 3 means to extract energy for the high current in the ring of elements: 1—a vibrating mechanical switch; 2—a Hall effect generator and; 3—a Colpits oscillator. Coatings of hot and cold elements of the thermoelectric device are claimed for selenium, tellurium and antimony among others but not for mixtures of these elements.
U.S. Pat. No. 6,222,242 to Konishi, et al., discloses semiconductor material of the formula AB.sub.2, X.sub.4 where A is one of or a mixture of Pb, Sn, or Ge, B is one of or a mixture of Bi and Sb and X is one of or a mixture of Te and Se. These represent Pb, Sn or Ge doped bismuth telluride.
U.S. Pat. No. 6,274,802 to Fukuda, describes a sintering method of making semiconductor material whose principle components include bismuth, tellurium and selenium and antimony.
U.S. Pat. No. 6,340,787 to Simeray discloses a thermoelectric component of bismuth doped with antimony and bismuth tellurium doped selenium wherein said component is arranged into a rod. Very low voltages are converted using a self-oscillating circuit.
U.S. Pat. No. 6,172,427 describes the use of a thermoelectric device on the exhaust portion of a combustion-based car using electrically driven wheel wherein excess heat energy is converted to electric power for the vehicle.